it's called balik ekmek, a grilled fish sandwich.the fish sandwiches in istanbul are an absolute must. with a view of bosphorus and the mosques, you can enjoy the ideal meal here. the fish goes well with karisik tursu, a mix of pickled vegetables, that you can buy on the neighboring stall. it's traditional to drink the vinegar, too. >> it's filling, and it's fish. and we're turkish -- we love fish. >> murat kahraman mans the grill on the asik family's boat. >> the fish is fried in its own fat, as you can see. what else do you add? well, a bit of onion and lettuce. that's the whole secret. >> i took over the shop from my father. i've been working here for the past 37 years, just like my forefathers. we love it. >> but the asik family shop doesn't sell the fish that's caught just off the galata bridge up above. this waterfront vendor has also kept pace with globalization. >> there's only one kind of fish -- norwegian mackerel. it comes in frozen and we prepare it here. the way it's fried, with the onions, the scent of the sea mixing wi